A large amount of plastic containers are used as containers for alcohol beverages, soft drinks, mineral waters and so on. Containers with a capacity of about 1 Liter (Liter is hereinafter symbolized as “L”) are easy to handle, but containers with a capacity of 2L or more are relatively difficult to handle because of their weight. Many of these containers are provided with a handle as a gripper for ease of carrying.
Beverage servers, which can chill and heat drinking water such as mineral water and deliver cold and hot water, are often seen in hotels, offices and so on. A drinking water supply bottle (which is hereinafter referred to as “drinking water bottle 1”) filled with mineral water or the like is coupled to a beverage server 2 with its opening down as shown in FIG. 1. Such a drinking water bottle 1 has a capacity of 5 to 20L, and needs a handle as a gripper (which is hereinafter referred to as “handle”) for ease of handling because of its size and weight. Such a drinking water bottle 1 often has a recessed body 17 as shown in FIG. 2 and a handle is attached in the recess 14 (which is hereinafter referred to as “recess of the drinking water bottle” or simply as “recess”) because the handle interfere with transportation and storage if it protrudes outward from the drinking water bottle. Although not shown, some bottles have a handle which is formed into a cylindrical shape along the vertical direction of the drinking water bottle in the recess at the same time as the drinking water bottle is formed and which can contain drinking water therein. The problem of the drinking water bottles with this structure is the difficulty of washing the inner wall of the cylindrical handle in the recess when the drinking water bottles are repeatedly used. Almost of all the drinking water bottles are fabricated by injection molding of a plastic material. Thus, it is contemplated to attach a separately prepared handle to a drinking water bottle having a recess. FIG. 3 shows the outline of the method. A hollow body 43 to be a container is formed with a blow mold 4. After a preform 1 of the hollow body 43 and a separately formed handle (not shown) are inserted into a proper position in the blow mold 4, compressed air 42 is fed into the preform 41. Then, the hollow body 43 is shaped and, simultaneously, the handle and outer surfaces of the hollow body 43 are engaged with each other, whereby the handle is attached to the hollow body 43.
That is, some handles for drinking water bottles have a grip portion extending along the vertical direction of the drinking water bottle and leg portions provided at upper and lower ends of the grip portion, and is attached to a drinking water bottle by engaging the leg portions with the outer surfaces of a recess of the drinking water bottle. The outer surfaces herein are the outer surfaces of large-thickness portions of the container forming a drinking water bottle. Some handles do not have the leg portions and are attached to a drinking water bottle by directly engaging both ends of the grip portion of the handle with the outer surfaces of the recess of the drinking water bottle. In the former case, the handle is attached to the drinking water bottle with projections provided on the leg portions of the handle fitted in depressions formed in the outer surfaces of the recess of the drinking water bottle. In the latter case, the handle is attached to the drinking water bottle with the grip portion of the handle fitted in depressions formed in the outer surfaces of the recess of the drinking water bottle. In addition, some drinking water bottles have a handle attached thereto by fitting both the grip portion and leg portions of the handle into depressions formed in the outer surfaces of the recess of the drinking water bottle. In any case, the attachment of the handle to the drinking water bottle is achieved by inserting a separately formed handle into a proper position in the blow mold for a drinking water bottle and carrying out blow molding as described above. Here, the term “handle” refers to the entire portion including the grip portion and leg portions (only the grip portion if the handle does not have the leg portions), and the terms “grip portion” and “leg portion” refer to the grip portion of a handle and the leg portion of a handle unless otherwise noted. Also, the corresponding portions of the strip-shaped handle part of the present invention are also referred to as “grip portion” and “leg portion.”
FIG. 4 is a partial view illustrating a handle 13 attached by engaging it with the outer surfaces 12 of the recess 14 of the drinking water bottle 1 when the drinking water bottle 1 is formed by blow molding. Stepped depressions (the contact regions 16 between the handle and the outer surfaces) to encompass both ends of the handle 13 are formed in recess top surface 14a and recess bottom surface 14b as the outer surfaces 12 of the recess 14 of the drinking water bottle 1 so that the handle can be attached to the drinking water bottle by engaging the both ends of the handle with the drinking water bottle. They are needed to secure the handle 13 to the drinking water bottle 1, and the blow mold (which may be hereinafter referred to simply as “mold” for the drinking water bottle 1 is fabricated in view of the stepped depressions to engage the both ends of the handle 13 with the drinking water bottle. When the drinking water bottle 1 is shaped, the molten resin flows into the gap around the ends of the handle 13 in the mold for the drinking water bottle but the molten resin does not flow smoothly around the contact regions 16 between the handle 13 and the outer surfaces as they have a stepped shape as described above and the portions of the drinking water bottle 1 tend to have a smaller thickness than other portions. In addition, since the molten resin moves in a complicated manner in these portions in the mold for the drinking water bottle during the shaping process, the stepped depressions are not be formed at the contact regions 16 between the handle and the outer surfaces in the recess of the drinking water bottle and the outer surface does not engage with the handle causing looseness in some cases, and, in other cases, the resin cannot flow into the spaces around the handle causing formation of a hole in the drinking water bottle, resulting in a high proportion defective in the injection molding process.
When emptied, the drinking water bottle 1 is refilled with drinking water and repeatedly used. With the above shaping method, the contact regions 16 between the handle and the outer surfaces have a smaller thickness as described above and thus has a lower strength. Therefore, the outer surfaces of the drinking water bottle 1 as the contact regions 16 between the handle and the outer surfaces may develop cracks or holes while the drinking water bottle 1 is continuously used. When the drinking water bottle develops cracks or the like, the following problem occurs.
In FIG. 1, the drinking water flows from the drinking water bottle 1 into a cold water tank 21 in the beverage server 2 through a joint 24. The cold water tank 21 has a partition 25 therein, and cooling pipes are located below the partition 25. The drinking water having flowed into the space under the partition 25 is cooled and stored in a cold water section 23. The drinking water having entered the cold water tank 21 is separated by the partition 25, some of which flows through a water conduit 27 into a hot water tank 22, and is heated by a heater 28 and stored in the hot water tank 22. The coldwater is delivered from a cold water port 29a, and the hot water from a hot water port 29b. The drinking water bottle 1 is coupled to the beverage server 2 with its opening down. Since a reduced pressure is generated in the drinking water bottle 1, the drinking water in the drinking water bottle 1 does not flow into the cold water tank 21 and the hot water tank 22 at once and the water levels in the cold water tank 21 and the hot water tank 22 are maintained constant even if the drinking water bottle is placed with its opening down. When an outer surface of the drinking water bottle has a crack or the like, since the reduced pressure in the drinking water bottle is released, the drinking water in the drinking water bottle flows into the cold water tank 21 and the hot water tank 22 at once and overflows from the cold water tank 21 and the hot water tank 22, losing the function of the beverage server 2. To avoid such a problem, it is necessary to increase the thickness of the contact regions 16 between the handle and the outer surfaces of the drinking water bottle 1 and to ensure close contact between the handle and the drinking water bottle so that the drinking water bottle 1 can withstand repetitive use. The term “close contact” herein refers to a state where the handle and the drinking water bottle are in close contact without any space therebetween.
On the other hand, some drinking water bottle are made of a material different from the material of their handles depending on the intended use. For example, some drinking water bottles are made of polyethylene terephthalate with their handles made of polypropylene. When broken drinking water bottles are disposed and reused, it is necessary to sort and collect different materials separately. However, when the drinking water bottle and the handle are engaged with and attached to each other, it takes time and labor to sort and collect different materials separately even if the materials used are different, making it difficult to recycle the materials.
As one method for providing a handle to a drinking water bottle, there is a container gripper which can be easily secured to a bottle with a capacity of about 2L (Patent Document 1). Another method is to form a recess in the body of the container and fit a handle in the recess along the vertical direction of the container so that it does not take space during storage and transportation (Patent Document 2). It is believed that both of the above can fulfill the function as a handle of a container with a capacity of about 2L. However, the drinking water bottles for use with beverage servers have a capacity of 5 to 20L, and these structures cannot provide sufficient strength.
Other examples include a plastic bottle having an opening formed through its body in the vicinity of a ridge part of the body so that the ridge part can be used as a handle (Patent Document 3), a container having a handle extending from the shoulder along a side wall of the container body to allow for insertion of fingers (Patent Document 4), and a container having recesses for better grip in the body of the container and a plurality of annular ribs below the recesses (Patent Document 5). In these inventions, expenses including the cost for a mold to fabricate the handled drinking water bottle are high, and there is a concern about the strength to handle containers with a capacity of 5 to 20L.
Furthermore, there is an application of a container having a body with a recess and a handle fitted in the recess such that the container and the handle can be easily separated (Patent Document 6). In this method, however, there remains concerns about the proportion defective in the process of injection molding of the containers, the strength of the contact regions between the handle and the outer surface of the container and so on as described above.    Patent Document 1: JP-A-2005-41513    Patent Document 2: JP-U-Hei 5-51730    Patent Document 3: JP-A-Hei 8-318921    Patent Document 4: JP-A-2001-146237    Patent Document 5: JP-A-2003-226315    Patent Document 6: JP-A-Hei 10-297635